Multicolored light emitting diode (LED) chips are commonly used in lighting applications where dynamic color mixing is desired. For example, the light from different colored LED chips can be mixed and their respective brightness adjusted to give white or most other colors. One of the challenges in these applications has been to mix the different colored LED chips without having unpleasant color fringing or shadowing. Dichroic color filters can be used to combine the different colored LED chips, but this is very expensive. In addition, the use of dichroic color filters only works with highly pre-collimated light, and is often inefficient.
A chamber with diffuse reflecting walls can also be used to mix the various colored light from multiple LED chips. The chamber has an aperture so that the mixed light can escape. This method also has significant light loss and is costly.